The major goals of this application are to trace the early development of temperament-related attentional systems and to relate these developments to the control of action and emotion. Using marker tasks identified in adult patients and by neural imaging, the applicant is able to relate behavioral findings to underlying neural systems. In this project she traces the development of an executive attention network that has been linked to frontal development. There is reason to believe this network plays a fundamental role, not only in the development of high level cognitive capacities, but in the self-regulation of emotional states and action. Because attentional self-regulation is such an important part of the socialization process, and because failures of self-regulation can result in behavioral problems and difficulties in school, research tracing the normal development of, and individual differences in, these controls has important implications for society. Two marker tasks are employed in this project involving 24- to 36-month-olds. The first is a spatial Stroop-like task investigating the resolution of conflicts between location and stimulus identity. The second involves learning sequences of locations where the correctness of the association depends upon context. Both of these tasks trace the ability to deal with competing response tendencies, a basic component of the executive attention network. Preliminary data show that these tasks can be made appropriate to measure the performance of children of this age and that they undergo important changes in this period. In a cross-sectional and a longitudinal study involving the further refinement of parent-report and laboratory temperament measures, the applicant proposes to estimate the time course of frontal development in connection with the ability to resolve attentional conflict. Performance on the marker tasks will also be related to other important aspects of temperament (inhibitory control and negative affectivity).